The invention relates to a colored borosilicate glass having a transmission in the near infrared range (NIR), which can be stepped to complete non-transparency, and the synthesis composition (in percent by weight on oxide basis) of SiO.sub.2 &gt;78, B.sub.2 O.sub.3 &gt;8, Al.sub.2 O.sub.3 1.5 to 3.5 and alkali oxide&gt;2.
The glasses are used especially as filters because of their absorption/transmission characteristic or as absorbers in solar technology if the light transmissibility in the NIR/IR range is sufficiently low.
It is known to color borosilicate glass in different ways by adding specific constituents. If glass with standardized characteristics is colored intensely, the disadvantage, however, often occurs with relatively large admixtures of coloring oxides (such as copper oxide, cobalt oxide, nickel oxide or manganese oxide) that important characteristics such as the expansion, the hydrolytic stability or the viscosity characteristics change to an impermissibly large extent.
It is furthermore not known to adjust stepped NIR transmissions with the above-listed coloring oxides and/or, in this way, to manufacture glass which is completely non-transmissible for sunlight.